Abstract
A vertex coloring of a graph G is called injective if every two vertices joined by a path of length 2 get different colors. The minimum number χ i (G) of the colors required for an injective coloring of a graph G is clearly not less than the maximum degree Δ(G) of G. There exist planar graphs with girth g ≥ 6 and χ i = Δ+1 for any Δ ≥ 2. We prove that every planar graph with Δ ≥ 18 and g ≥ 6 has χ i ≤ Δ + 1.
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Original Russian Text Copyright © 2011 Borodin O. V. and Ivanova A. O.
The authors were supported by the Russian Foundation for Basic Research (Grants 09-01-00244 and 08-01-00673). The second author was also supported by a grant of the President of the Russian Federation for Junior Scientists (Grant MK-2302.2008.1).
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Novosibirsk; Yakutsk. Translated from Sibirskiĭ Matematicheskiĭ Zhurnal, Vol. 52, No. 1, pp. 30–38, January–February, 2011.
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Borodin, O.V., Ivanova, A.O. Injective (Δ + 1)-coloring of planar graphs with girth 6. Sib Math J 52, 23–29 (2011). https://doi.org/10.1134/S0037446606010034
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DOI: https://doi.org/10.1134/S0037446606010034